HALIFAX -- A sole female case worker was rushed by a group of youth swinging their fists and forcing her down to the floor as a riot unfolded last Sunday, leaving staff with fear about safety practices at the Nova Scotia youth facility, says a union leader.

Jason MacLean, president of the Nova Scotia Government and General Employees Union, gave a more detailed description Friday of the incident that escalated and ended with injuries to five youth workers -- including broken bones, bruises and cuts.

"These were very large individuals ... They came swinging at her and hit her," he said, after he held meetings with over 40 staff from the Waterville facility, with some of the bruised and bandaged staff sitting in the Thursday evening gathering.

One of the youth workers continued to urge the youth to calm down during the incident, even as he was struck and injured, said MacLean.

The union president, himself a corrections worker, says he was told the incident began at a shift change, as one youth rang a buzzer to go to the bathroom.

He says the female youth worker used a "gang door" buzzer, which allows all doors to open at once and permitted the youth to come pouring out as she desperately called for help on a radio system.

The offenders also broke open one of the wooden doors, allowing another youth to participate in the melee, he added.

MacLean says staff told him the youth involved didn't possess weapons, but used their fists and feet to strike and kick three female youth workers and two male youth workers at the scene in the cottage-style building in the Annapolis Valley.

MacLean says he's been told of safety concerns including a dysfunctional occupational health and safety committee, repeated complaints about the "gang door" system, and incompatible mixtures of young people being housed in the same area.

"What I'm learning is that the health and safety committee hasn't been working ... I don't believe they were working regularly and I don't believe concerns were being addressed through the committee," he said.

The province had declined to comment on details of the incident, saying there will be an investigation and a report issued.

However, Justice Minister Diana Whalen has said there are sufficient staff for the 23 residents, with 81 people currently working at Waterville.

MacLean says he was told staff accompany some youth during leave in the community, reducing the weekend complement of staff.

The union leader also says he heard from staff that days before the incident they warned that the mix of youth in the cottage could lead to trouble, and that there had been undocumented requests to management to split up the group.

The union is looking to begin bringing in safety changes immediately, including better protective equipment, changes to staffing complements, stronger doors and a change to the "gang door" system, said MacLean.

MacLean has said he has requested a meeting with the Public Service Commission for next week.

One 18-year-old man is charged with taking part in a riot and two counts of assault while carrying a weapon, while a 19-year-old man is charged with taking part in a riot and damage to property.

Two 17-year-old males were also arrested, and later returned to the youth facility.